Furthermore, we demonstrated that the level of survival factor Bcl-2 upregulated by Ad.4N1 could be suppressed by the deletion of viral E1B and further harboring IL-24, and Ad.4N1-IL24 replicated at a dramatically higher rate than Ad.4N1, which may be responsible for the higher antiproliferative effect of Ad.4N1-IL24 on leukemia cells. Here, BCL2 is linked to leukemia.